The present invention relates to an optical magnetic memory device having magnetic film as a recording medium and which records., reproduces and/or erases data by irradiating the recording medium with an optical beam such as a laser beam.
Conventionally, two types of optical magnetic disc are known as typical optical memory devices; one having magnetic film only on one side thereof and the other having magnetic film on both sides as a recording medium. When data in a disc with magnetic film on both sides is to be reproduced by the conventional optical magnetic memory device capable of reproducing data from the disc with magnetic film only on one side, data in one of the magnetic films may be reproduced but it is unlikely that data in the other magnetic film will be reproduced satisfactorily.
Generally, in recording data with an optical magnetic memory device, recorded bits and non-recorded bits are formed in the recording medium (disc) with magnetic film thereon. The memory device reproduces the data by detecting the interval between the recorded bits (non-recorded portions) as reference marks. However, a data signal obtained by this reproduction process may not be reliable.